Alternating-current potential switch.



D. LARSON. ALTERNATING CURRENT POTENTIAL SWITCH.

APPLIOATION FILED MAY 7, 1908.

Patented Jan. 17, 1911.

2 SHEETS-SHEET 1.

ATTORNEY I I M.

2 JYKYQ D. LARSON. ALTERNATING GURRBNT POTENTIAL SWITCH.

APPLIGATION FILED MAY 7, 1908. v

v Patented Jan. 17,1911.

' 2 SHEETS-SHEBT 2.

source of current supply switch is adapted to be closedv by UNITED STATES PATENT OFFICE.

DAVID llARSON, 0F YONKERS, NEW YORK, ASSIGNOR TO OTIS 0F JERSEY CITY, NEW JERSEY, A CORPORATION OF ELEV ATOR COMPANY, NEW JERSEY.

ALTERNATING-CUBRENT I POTENTIAL SWITCH.

Specification of Letters Patent.

Patented Jan. 17, 1911.

Application filed May 7, 1908. Serial No. 431,497.

To all whom it may concern:

Be it known that 1, DAVID LARSON, a sub .ject of the King of Sweden, residing at Yonkers in the countv of \Ves-tchester and State of New York have invented a new and useful Improvement in Alternating- Current Potential Switches, of which the following is a specification.

My invention relates to electromagnetic switches, and particularly to switches controlled by alternating current magnets.

One of the objects of the invention is to provide a switch of this kind in which only a small electromagnet and one consuming onl a small amount of current is required to iold the switch closed, and which at the same time will be free from the chattering noise ordinarily accompanying the use of alternating current magnets.

Other objectsof the invention will appear hereinafter, the novel combinations of elements being set forth in the appended claims.

Referring to the accompanying drawings, Figure 1 is a side elevation partly in section of an electromagnetic switch mechanism embodying my invention; Fig. 2 is a.

front elevation of the same Fi 3 is a secshown is what is commonly known in the art as a otential switch,- and is adapted to be place and the apparatus operated or controlled by the current. The hand, and is then held in such position by the electromagnet until the line potential falls below a predetermined value, when the switch is automatically opened. As a switch of this kind is normally held closed and is often retained in such position continuously for long periods of time, considerable electrical energy is usually consumed, and it is one of the special objects of the present invention to so design and arrange the parts that the switch contacts may be held firmly in engagement by a comparatively weak mag- 'netic pull, requiring only a small magnet,

and at the same time to provide an electro magnet that shall be eflicient when used with between the mains leading to a of the magnet ment of the switch arm as shown in dotted I lines. The switch is provided with two pairs of contacts, as indicated in Fig. 2. The stationary switch contacts 9 are held between clamping jaws l0 and 11, the jaws 10 extending through the base and forming binding posts 12. The movable contacts 13 are each provided with a stem 14 extending through a lateral projection 15 of the switch arm and forming a binding post. As the particular construction of the contacts and means for mounting the same form ro part of the present invention, a detailed description thereof need not be given herein. Any other suitable form of contacts may be used, if desired. Conductors leading to the apparatus to be controlled by the switch may be connected to the binding posts 12, the circuit being completed in the usual way through the flexible cables 1G, 16' connected to the potential mains.

The switch magnet. M comprises a frame member 17 of magnetic material secured to the base 1 by bolts 18'. Bolted to the men ber 17 is a series of laminated plates 19 having projecting portions 20 extending into the magnet spool or winding an inner pole piece of the magnet. The spool 21 may be secured in position by a key 22 extendin through the spool and bolted with the plates 19 to the member ii. The armature or movable portion 28 of the magnet core is also laminated, and, as here-- In order to absorb the vi current alternations, and thus prevent chattering, the follt'iwing means is provided. A rod is 511 eaded into the member 17 .ramc a nd may be usted by means of the knurled head 26 a coke-d in position by a nut A cylind al projection or core 27 extending outwardly from the head 26 forms a support for a hea coil spring 2t, the inner end of which tightly wedged or chap ed in a recess 2o 11 21, and forming the core 27, thereby securely holding the spring against. displacement. Formed on the inner face of the switch arm opposite the spring 28 is a lug 30 which is recessed to receive the end of the coil spring when the switch is closed. The rod 24 and spring 28 being made of magnetic material, form a path for the magnetic lines of force around Plates 32 and 33 of asbestos wood, or other' fireproof insulating material, may be used if desired to deflect arcs that might be produced at the contacts. A handle 34 is pro vided for closing they switch. When the switch is closed, the coil spring 28 forms a yielding abutment for the switch arm, as the spring is strong enough to permit only a slight compression under the pull of the magnet, and'the position of said spring determines the width of the air gap between the magnet poles. The rod 24 is usually so adjusted that only a small air gap is maintained between the magnet poles. The outer end of the spring 28 entering the recess in the lug 30 holds the switch arm 6 against any displacement that might occur owing to looseness in the pivotal connection of the switch arm, and thus holds the magnet core ,13 in central position. The spring "28 absorbs all vibration of the switch arm caused by current alternations in the magnet coil, .and the switch ai m is made quite heavy so thatrits inertia will prevent excessive vibration. The switch contacts 9 and 13 are yieldingly held in engagement by the coil spring 35 which etfects such engagement irrespective of the adjustment of the spring 28. It should also be noted that the rod 5 is held firmly in its bearings due to the leverage arrangement.

It will be noted that the switch contacts are located near the fulcrum of the switch arm or lever (5, while the magnet is located at the outer end of the switch arm. By this arrangement a small magnet, owing to the leverage obtained, is able to firmly hold the switch contacts together. The amount of current consumed is also much less than in the usual arrangement.

. I have-herein shown a construction embodying my invention in one form, but various changes in details of construction and arrai'igenient of parts might. be made by those skilled in the art without departing from the spirit and scope of the invention, and I-wish therefore not to be limited to the precise construction disclosed.

What I claim as new and desire to secure by Letters Patent of the United States is 1. I11 an electromagnetic switch, the combination with a base, of a magnet coil, a magnet frame secured to the base and having a pole piece extending into said coil, a switch arm made of magnetic material, a pole piece carried thereby and movable into said coil, and means for completing the magnetic circuit outside of said coil and through the switch arm.

2. In an electromagnetic switch, the combination of a switch arm, an electromagnet, an armature for said electromagnet carried by the switch arm, a base on which the electromagnet is mounted, said base being provided with a threaded opening, a threaded rod adjustably mounted in said opening,

lock nut for said rod, a stiff coil spring mounted on said rod and a lug formed on the switch arm, and provided with a recess to receive the end of said spring, said spring being positioned to hold the armature out of contact with the magnet when the armature is in its attracted position.

In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses.

DAVID LARSON.

\Vitnesses CHAS/l. NISSEN, T\MF.R IVERS. 

